1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Altera PCIe MSI support
4 *
5 * Author: Ley Foon Tan <lftan@altera.com>
6 *
7 * Copyright Altera Corporation (C) 2013-2015. All rights reserved
8 */
9
10 #include <linux/interrupt.h>
11 #include <linux/irqchip/chained_irq.h>
12 #include <linux/irqchip/irq-msi-lib.h>
13 #include <linux/irqdomain.h>
14 #include <linux/init.h>
15 #include <linux/module.h>
16 #include <linux/msi.h>
17 #include <linux/of_address.h>
18 #include <linux/of_pci.h>
19 #include <linux/pci.h>
20 #include <linux/platform_device.h>
21 #include <linux/slab.h>
22
23 #define MSI_STATUS 0x0
24 #define MSI_ERROR 0x4
25 #define MSI_INTMASK 0x8
26
27 #define MAX_MSI_VECTORS 32
28
29 struct altera_msi {
30 DECLARE_BITMAP(used, MAX_MSI_VECTORS);
31 struct mutex lock; /* protect "used" bitmap */
32 struct platform_device *pdev;
33 struct irq_domain *inner_domain;
34 void __iomem *csr_base;
35 void __iomem *vector_base;
36 phys_addr_t vector_phy;
37 u32 num_of_vectors;
38 int irq;
39 };
40
msi_writel(struct altera_msi * msi,const u32 value,const u32 reg)41 static inline void msi_writel(struct altera_msi *msi, const u32 value,
42 const u32 reg)
43 {
44 writel_relaxed(value, msi->csr_base + reg);
45 }
46
msi_readl(struct altera_msi * msi,const u32 reg)47 static inline u32 msi_readl(struct altera_msi *msi, const u32 reg)
48 {
49 return readl_relaxed(msi->csr_base + reg);
50 }
51
altera_msi_isr(struct irq_desc * desc)52 static void altera_msi_isr(struct irq_desc *desc)
53 {
54 struct irq_chip *chip = irq_desc_get_chip(desc);
55 struct altera_msi *msi;
56 unsigned long status;
57 u32 bit;
58 int ret;
59
60 chained_irq_enter(chip, desc);
61 msi = irq_desc_get_handler_data(desc);
62
63 while ((status = msi_readl(msi, MSI_STATUS)) != 0) {
64 for_each_set_bit(bit, &status, msi->num_of_vectors) {
65 /* Dummy read from vector to clear the interrupt */
66 readl_relaxed(msi->vector_base + (bit * sizeof(u32)));
67
68 ret = generic_handle_domain_irq(msi->inner_domain, bit);
69 if (ret)
70 dev_err_ratelimited(&msi->pdev->dev, "unexpected MSI\n");
71 }
72 }
73
74 chained_irq_exit(chip, desc);
75 }
76
77 #define ALTERA_MSI_FLAGS_REQUIRED (MSI_FLAG_USE_DEF_DOM_OPS | \
78 MSI_FLAG_USE_DEF_CHIP_OPS | \
79 MSI_FLAG_NO_AFFINITY)
80
81 #define ALTERA_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK | \
82 MSI_FLAG_PCI_MSIX)
83
84 static const struct msi_parent_ops altera_msi_parent_ops = {
85 .required_flags = ALTERA_MSI_FLAGS_REQUIRED,
86 .supported_flags = ALTERA_MSI_FLAGS_SUPPORTED,
87 .bus_select_token = DOMAIN_BUS_PCI_MSI,
88 .prefix = "Altera-",
89 .init_dev_msi_info = msi_lib_init_dev_msi_info,
90 };
altera_compose_msi_msg(struct irq_data * data,struct msi_msg * msg)91 static void altera_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
92 {
93 struct altera_msi *msi = irq_data_get_irq_chip_data(data);
94 phys_addr_t addr = msi->vector_phy + (data->hwirq * sizeof(u32));
95
96 msg->address_lo = lower_32_bits(addr);
97 msg->address_hi = upper_32_bits(addr);
98 msg->data = data->hwirq;
99
100 dev_dbg(&msi->pdev->dev, "msi#%d address_hi %#x address_lo %#x\n",
101 (int)data->hwirq, msg->address_hi, msg->address_lo);
102 }
103
104 static struct irq_chip altera_msi_bottom_irq_chip = {
105 .name = "Altera MSI",
106 .irq_compose_msi_msg = altera_compose_msi_msg,
107 };
108
altera_irq_domain_alloc(struct irq_domain * domain,unsigned int virq,unsigned int nr_irqs,void * args)109 static int altera_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
110 unsigned int nr_irqs, void *args)
111 {
112 struct altera_msi *msi = domain->host_data;
113 unsigned long bit;
114 u32 mask;
115
116 WARN_ON(nr_irqs != 1);
117 mutex_lock(&msi->lock);
118
119 bit = find_first_zero_bit(msi->used, msi->num_of_vectors);
120 if (bit >= msi->num_of_vectors) {
121 mutex_unlock(&msi->lock);
122 return -ENOSPC;
123 }
124
125 set_bit(bit, msi->used);
126
127 mutex_unlock(&msi->lock);
128
129 irq_domain_set_info(domain, virq, bit, &altera_msi_bottom_irq_chip,
130 domain->host_data, handle_simple_irq,
131 NULL, NULL);
132
133 mask = msi_readl(msi, MSI_INTMASK);
134 mask |= 1 << bit;
135 msi_writel(msi, mask, MSI_INTMASK);
136
137 return 0;
138 }
139
altera_irq_domain_free(struct irq_domain * domain,unsigned int virq,unsigned int nr_irqs)140 static void altera_irq_domain_free(struct irq_domain *domain,
141 unsigned int virq, unsigned int nr_irqs)
142 {
143 struct irq_data *d = irq_domain_get_irq_data(domain, virq);
144 struct altera_msi *msi = irq_data_get_irq_chip_data(d);
145 u32 mask;
146
147 mutex_lock(&msi->lock);
148
149 if (!test_bit(d->hwirq, msi->used)) {
150 dev_err(&msi->pdev->dev, "trying to free unused MSI#%lu\n",
151 d->hwirq);
152 } else {
153 __clear_bit(d->hwirq, msi->used);
154 mask = msi_readl(msi, MSI_INTMASK);
155 mask &= ~(1 << d->hwirq);
156 msi_writel(msi, mask, MSI_INTMASK);
157 }
158
159 mutex_unlock(&msi->lock);
160 }
161
162 static const struct irq_domain_ops msi_domain_ops = {
163 .alloc = altera_irq_domain_alloc,
164 .free = altera_irq_domain_free,
165 };
166
altera_allocate_domains(struct altera_msi * msi)167 static int altera_allocate_domains(struct altera_msi *msi)
168 {
169 struct irq_domain_info info = {
170 .fwnode = dev_fwnode(&msi->pdev->dev),
171 .ops = &msi_domain_ops,
172 .host_data = msi,
173 .size = msi->num_of_vectors,
174 };
175
176 msi->inner_domain = msi_create_parent_irq_domain(&info, &altera_msi_parent_ops);
177 if (!msi->inner_domain) {
178 dev_err(&msi->pdev->dev, "failed to create MSI domain\n");
179 return -ENOMEM;
180 }
181
182 return 0;
183 }
184
altera_free_domains(struct altera_msi * msi)185 static void altera_free_domains(struct altera_msi *msi)
186 {
187 irq_domain_remove(msi->inner_domain);
188 }
189
altera_msi_remove(struct platform_device * pdev)190 static void altera_msi_remove(struct platform_device *pdev)
191 {
192 struct altera_msi *msi = platform_get_drvdata(pdev);
193
194 msi_writel(msi, 0, MSI_INTMASK);
195 irq_set_chained_handler_and_data(msi->irq, NULL, NULL);
196
197 altera_free_domains(msi);
198
199 platform_set_drvdata(pdev, NULL);
200 }
201
altera_msi_probe(struct platform_device * pdev)202 static int altera_msi_probe(struct platform_device *pdev)
203 {
204 struct altera_msi *msi;
205 struct device_node *np = pdev->dev.of_node;
206 struct resource *res;
207 int ret;
208
209 msi = devm_kzalloc(&pdev->dev, sizeof(struct altera_msi),
210 GFP_KERNEL);
211 if (!msi)
212 return -ENOMEM;
213
214 mutex_init(&msi->lock);
215 msi->pdev = pdev;
216
217 msi->csr_base = devm_platform_ioremap_resource_byname(pdev, "csr");
218 if (IS_ERR(msi->csr_base)) {
219 dev_err(&pdev->dev, "failed to map csr memory\n");
220 return PTR_ERR(msi->csr_base);
221 }
222
223 res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
224 "vector_slave");
225 msi->vector_base = devm_ioremap_resource(&pdev->dev, res);
226 if (IS_ERR(msi->vector_base))
227 return PTR_ERR(msi->vector_base);
228
229 msi->vector_phy = res->start;
230
231 if (of_property_read_u32(np, "num-vectors", &msi->num_of_vectors)) {
232 dev_err(&pdev->dev, "failed to parse the number of vectors\n");
233 return -EINVAL;
234 }
235
236 ret = altera_allocate_domains(msi);
237 if (ret)
238 return ret;
239
240 msi->irq = platform_get_irq(pdev, 0);
241 if (msi->irq < 0) {
242 ret = msi->irq;
243 goto err;
244 }
245
246 irq_set_chained_handler_and_data(msi->irq, altera_msi_isr, msi);
247 platform_set_drvdata(pdev, msi);
248
249 return 0;
250
251 err:
252 altera_msi_remove(pdev);
253 return ret;
254 }
255
256 static const struct of_device_id altera_msi_of_match[] = {
257 { .compatible = "altr,msi-1.0", NULL },
258 { },
259 };
260
261 static struct platform_driver altera_msi_driver = {
262 .driver = {
263 .name = "altera-msi",
264 .of_match_table = altera_msi_of_match,
265 },
266 .probe = altera_msi_probe,
267 .remove = altera_msi_remove,
268 };
269
altera_msi_init(void)270 static int __init altera_msi_init(void)
271 {
272 return platform_driver_register(&altera_msi_driver);
273 }
274
altera_msi_exit(void)275 static void __exit altera_msi_exit(void)
276 {
277 platform_driver_unregister(&altera_msi_driver);
278 }
279
280 subsys_initcall(altera_msi_init);
281 MODULE_DEVICE_TABLE(of, altera_msi_of_match);
282 module_exit(altera_msi_exit);
283 MODULE_DESCRIPTION("Altera PCIe MSI support driver");
284 MODULE_LICENSE("GPL v2");
285